Effectiveness of the interventions against workplace violence suffered by health and support professionals: A meta-analysis

Abstract Objective: to assess the effectiveness of the interventions targeted at preventing and reducing the workplace violence suffered by health and support professionals. Method: a systematic review with meta-analysis conducted in eight databases and in the gray literature. Risk of bias was assessed by means of the Cochrane tools and certainty of the evidence, through Grading of Recommendations Assessment, Development and Evaluation. The analysis was performed in a descriptive manner and through the meta-analysis, including a heterogeneity assessment. Results: a total of 11 randomized and quasi-randomized studies were eligible, of which six (54.5%) implemented individual skills, four used a multiple approach (36.4%) and one (9.1%) resorted to governmental actions. Four studies (36.4%) exerted a positive and significant effect on reducing violence. Risk of bias was classified as high or uncertain. The meta-analysis was performed with two studies that tested individual skill (intervention group) versus individual skill (comparator group), although there was no scientific evidence (95% CI: -0.41 - 0.25, p=0.64) for the violence prevention/reduction outcome. Conclusion: this review did not obtain a high level of evidence in the prevention or reduction of workplace violence. The reduced number of randomized trials, the lack of studies with low risk of bias and the high consistency may have been factors that hindered recommending effective interventions.

A number of studies also reveal that the aforementioned violence in the health sector especially affects female professionals and the Nursing category that practices their profession, especially in hospitals, emergency departments and without another coworker (8)(9)(10)(11) .
In order to combat this complex phenomenon, several institutions and international bodies have been publishing guidelines to eliminate it with a focus on a zero tolerance culture, addressing measures to minimize or exclude the workplace violence rates and risk. Such measures include commitment by the management, participation of the professional, workplace analysis, safety and health training, risk factor analysis and monitoring records of the violence rates (2,(7)(8) .
Thus, actions and implementation of guidelines, laws or public policies to reduce violence should be sought, as it is a preventable problem and an important determinant of physical illness and, above all, mental ailments (12) .
Among the systematic reviews that sought to identify the effect of the interventions, it was verified that there is lack of knowledge in the studies about the effectiveness of the actions that prevent or reduce acts of violence against professionals working in the health services. It should be noted that one study only evaluated a specific intervention at the individual level, including education and training (13) and another did so at the organizational level, such as work programs and practices (14) .
In view of the aforementioned considerations, this study is justified, as identifying the scientific evidence on the theme will contribute to the standardization of effective interventions that may curb and prevent acts of violence that affect health and support professionals.
Thus, the objective of this systematic review was to assess the effectiveness of the interventions targeted at preventing and reducing the workplace violence suffered by health and support professionals.

Method Study design
This study is a systematic review with meta-analysis written according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (15)(16)(17) . The protocol of this review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) platform under number CRD42018111383 (18) . This protocols was also published in the BMJ Open Journal (19) .

Selection criteria
To search for studies and formulate the guiding question, the PICOS (20) strategy was used, an acronym for "Population" (health and support professionals), The inclusion criteria adopted addressed studies: 1) conducted with health and/or support professionals (21) ; 2) carried out in health services or community health services, such as hospitals, emergency sectors, basic health units or long-term care institutions, in addition to the patient's home; 3) addressing organizational, environmental, individual, multiple approach (organizational, environmental and individual) or governmental interventions (7) ; 4) that had reduction and/or prevention of workplace violence perpetrated by patients as primary or secondary outcomes; 5) with randomized or quasi-randomized designs such as randomized clinical trials (level II evidence) and quasirandomized studies (such as before-and-after type with a control group, level III evidence) (22)(23)(24) . No restriction was applied in relation to language or year publication.
The exclusion criteria adopted addressed studies: 1) conducted with residents and/or students; 2) with review methodologies, letters, personal opinions, book chapters, institutional manuals, reports, case series, crosssectional studies (non-comparative as the before-and-after type without control group); and 3) with duplicate data.

Period
Data collection took place during 2020 and 2021. A search in the databases was conducted on August 8 th , 2020. Another updated search was performed on June 9 th , 2021.

Data collection
The individual search strategies for each electronic database were implemented in PubMed, Scopus, Web of Science, EMBASE, the Cochrane Library, CINAHL, LILACS and Livivo. In addition to that, searches were also conducted in the gray literature, including Google Scholar, OpenGrey and ProQuest. The strategy was prepared by the research team of this review, including PhDs on the theme and on the review method.
It is noted that, prior to carrying out the final searches of the primary studies in the databases selected, several combinations were made employing the controlled descriptors, keywords and the AND and OR Boolean operators. The objective was to identify the highest possible number of publications, first in the PubMed database with adaptation for the others. The MeSH descriptors included the following: "health personnel", "attitude of health personnel", "workplace violence", "exposure to violence", "physical abuse" and "education", in addition to synonyms and keywords. The search was conducted by two researchers with PhD degrees on the theme of violence, as well as on the method adopted for the study.
A manual search was also conducted in the references of all the articles included. An expert on the topic of "workplace violence" was identified via a website (http:// expertscape.com/), contacted by email and asked to identify the five most important publications on the topic.
The studies were first exported by a PhD to EndNote online (25) , where a detailed screening of all studies and references was performed and duplicates were removed.
Subsequently, the citations were exported by the same PhD to the Rayyan QCRI manager (26) , with a new process for removal of duplicates; and selection of the studies, in two phases, was performed by two reviewers.
In the first selection phase, two masked reviewers (one with a Master's degree and the other with a PhD) independently read and evaluated the titles and abstracts of all studies, applying the eligibility criteria to define the studies to be included. In the second phase, these same reviewers read the full texts to confirm eligibility.
Data extraction and collection was in charge of another two reviewers (with Master's and PhD degrees, respectively), masked and by means of a form. This form contained a number of study characteristics (author, year, country, study design, objective, locus, study period), population (category, gender, sample size), characteristics of the results (intervention and control groups, including the total sample number of these groups (n) and a description of the intervention and control, randomization, blinding, main results) and main conclusion. A maximum of three attempts were made to contact the authors of the studies to retrieve the information. Subsequently, data accuracy was confirmed between the reviewers.
Any and all disagreements were resolved in a meeting between both reviewers. If no consensus was reached, another two reviewers (PhDs) with expertise in the topic of worker's health and in the method were contacted to resolve the differences in the aforementioned phases (data collection, selection of the studies and/or extraction). Two masked reviewers (master's degree and PhD) evaluated each domain (selection, performance, detection, attrition and reporting) and classified each study as high risk, low risk or some concerns regarding bias, based on the aforementioned tools.

Results
In the first phase of this review, 4,909 citations were identified in eight databases, mentioned in the method.
Subsequently, after removing the 1,963 duplicate citations, the titles and abstracts of 2,946 articles were assessed to apply the eligibility criteria. Thus, 2,903 studies were included in phase 1. Complementarily, searches were conducted in the gray literature, the reference lists of the articles included were read and the experts were consulted, with addition of another 144 articles to the first phase. Of these, nine were included for the second phase: full-reading.
A total of 52 articles (43 from the databases and 9 found through other methods) were eligible for the second phase. Of these, 41 were excluded after full-reading. An updated search, carried out on 06/09/2021, provided two studies to be screened for full-text reading, but they were excluded after adoption of the eligibility criteria. Therefore, 11 studies were included for the descriptive analysis. Figure 1 presents a detailed flowchart of the process corresponding to the identification, inclusion and exclusion of studies according to the PRISMA guidelines (17) . The studies included were conducted in five countries: Sweden (35) , United States of America (36)(37)(38)(40)(41)(42)(43) , Canada (39) , Iran (44) and New Zealand (45) , with most of them (63.7%) from the United States of America. The studies were published between 2000 and 2019.
Regarding the methodology adopted, seven (63.7%) studies (35-39,41,44) were classified as quasi-randomized and four (36.3%) studies (40,(42)(43)45) as randomized clinical trials, one of the classic type (42) and three of the cluster type (40,43,45) . Duration of these studies did not present a pattern, but varied between four and 1,440 months, and the intervention took place between one and 360 months after the beginning of the study.
The main descriptive characteristics of the articles included are presented in Figure 2.
Gates, Fitzwater, Quasirandomized Individual skills (lectures, discussions with videos, demonstrations and problem-solving) (n= 53) The intervention did not exert any significant effect on the incidence of aggressions.
Anderson (37) 2006 Quasirandomized Individual skills (online training containing risk assessment, assertiveness techniques, and ethical and legal questions) (n=22) Only verbal abuse was statistically significant between the IG* (intervention concluded in 30 days) and the CG † , with a decline in the number of events.
Casteel, et al. (38) 2009 Quasirandomized The policy (state law) can be an effective method to improve health professionals' safety.
Kling, et al. (39) 2011 Quasirandomized Multiple approach (Training of an electronic patient alert system, containing risk assessment and courses of action after signaling those at risk of WPV § , such as nearby security guards) (n=109) None (n=634) The Alert System did not prevent WPV § incidents by the patients after being signaled, as the rates only decreased during the implementation period for this system.

Very low
Source: Chart elaborated in and extracted from the GRADEpro ® software (34) . * Two levels decreased due to uncertain risk of bias in both studies, in the "intervention deviation" and "general" domains; † Two levels decreased, as I 2 =88%; ‡ One level decreased due to the difference in the direction of the effect of the confidence intervals of both studies; § CI = Confidence Interval; || MD = Mean Differences In relation to the randomized clinical trials, of the four studies included, three (75%) were classified as (un) certain risk (40,(42)(43) , while one (25%) was categorized as high risk (45) due to concerns about deviations from the intended intervention (domain 2), missing data (domain 3) and measurement of outcomes (domain 4).
Regarding the seven quasi-randomized studies analyzed by means of ROBINS-I (29)(30) , five (71.4%) were classified as serious risk (34,37,39,41,44) , one (14.3%) as moderate risk (38) and another one ( In order to assess the possibility of meta-analysis, the first step was to group the studies according to the PICOS acronym. Thus, the (methodologically and clinically) homogeneous studies were combined, resulting in the meta-analysis of two studies (40,42) . Heterogeneity was considered important (I²=88%). The estimate corresponding to the mean of the random effect of the studies was -0.08 and the meta-analysis diamond 95% CI

Discussion
The studies found in this review reveal that most of programs to prevent it. The documents were gradually updated and the last one was published in 2016 (8) .  (10) .
A systematic review with meta-analysis revealed that female nurses are more likely (21%) to being victims of verbal harassment than their male counterparts (49) .
In relation to another review, it was verified that there are more chances for women being victims of sexual harassment when compared to men (50) . Among the existing theories that seek to explain the phenomenon of workplace violence, an interactive and theoretical model shows that it has a multifaceted nature and that it can be understood through the interaction of several interrelated factors such as individual, social, environmental and occupational ones (51) . This theory reveals that the victim's gender, age, task situation and working without any other colleague (from home) can exert an influence on the occurrence of violence.
Together, other risk factors such as individual issues inherent to the aggressor (e.g., use of illegal substances) and social and contextual factors (e.g., violence in society, negative culture of violence and insecurity at work) can influence the outcome of violence (physical and/ or psychological) both for the workers, including stress, diseases and health problems, high costs and suicide, and for the employing institution, including absenteeism and the quality of the care provided to the patients (51)(52) .
A fact that furthers aggravates the magnitude of the problem of the aforementioned type of violence is its underreporting (2,53) . A study carried out in a North American hospital system with approximately 15,000 employees concluded that 88% of the professionals had not recorded any incidents in the electronic system that is used in the United States of America for notification, where incidents that caused injuries were mainly reported (53) . Thus, underreporting is even more alarming in cases of harassment and abuse, possibly due to the culture of trivializing violence in the workplace, considered by many to be common in the health sector (51) .
Notification of violence still needs to advance to determine the extent and depth of this problem, including preventive measures and interventions that can support health professionals so that they report violence and are protected against reprisals, both at work and from the aggressor (54) . A research study verified that the clinical outcomes can improve, especially after 12 months of study (22) .
Thus, a study (37) published in 2006 was significant, although only for data on verbal abuse, with a study period of 12 months, 6 months post-intervention (online training). In another study (38) published in 2009, with 108 months of study, implementation of the policy was able to significantly increase the health professionals' safety 72 months after the intervention.
For the randomized clinical trials, a study (43) published in 2017 was also effective and significant in reducing the risks of patient-worker violence and related injuries after the 24-month period since implementation of the intervention, with a 60-month study period. In another randomized clinical trial (42) , computer-based training also reduced incidents of violence and harassment in the workplace, although with no significant difference between the groups. In this study (42) , time corresponded to 6 months, and the intervention took place 2 months after initiating the study. Thus, it is inferred that monitoring time can be related to the significance of the effect of the intervention.
A systematic review conducted with nine randomized and quasi-randomized studies concluded that the diverse scientific evidence is extremely uncertain about the effects of education and training on aggression in the shortterm follow-up when compared to no intervention. In the long-term, education was not able to reduce the violence rates in relation to no intervention (low certainty of the evidence) (13) .
The interventions classified in this study were defined according to the International Labor Organization (7) , Among the randomized clinical trials, two studies (40,43) exerted significant effects on the violence rates. A study (40) published in 2012 implemented an individual skill approach, including an Internet training session designed to teach strategies through courses with videos demonstrating behaviors, in a one-week period, to nursing assistants, in both groups, IG and CG, but with different intervention times, in order to deal with, prevent or reduce aggressive behaviors by institutionalized aged individuals.
In the IG, training was performed immediately after the beginning of the study, while in the CG, it was conducted after 8 weeks, with the study lasting 6 months.
Another research study (43)  This participant research method is widely accepted in health care and consists of a scientific method to test changes in complex environments (55) . A systematic review found that this methodology can be effective, as shown by a study (43) included in this review, although it needs to be implemented rigorously (55) .
Similarly, two quasi-randomized studies included in this review proved to be effective and significant. A study (37) found that a three-hour online training session (individual skills development), focusing on violence risk assessment, assertiveness techniques, legal issues and monitoring after an incident, was significant, although only for verbal abuse rates; whereas another study (38) , It is therefore understood that the guidelines are essential, but a regulatory norm, with a mandatory character, has greater coercive conditions for the implementation of preventive measures against workplace violence.
The implementation of governmental interventions, including legal aspects or public policies, at the local, municipal, regional, state or national level is an effective strategy with high potential to address workplace violence in the health services in a collective and sustainable way (56) . Such being the case, governmental interventions and efforts must be implemented so that a safe and decent work environment is promoted.
Despite the efforts in different countries or locations, many places do not yet have legislation or public policies that ensure specific strategies to prevent workplace violence against health professionals (56)  It is noted that the different periods of the interventions implemented in the studies described above can interfere with their effectiveness. In addition to that, effectiveness can also be affected by the follow-up time of the studies, as research has found that the outcomes can improve with increased study follow-up times (22) . Another explanation can be due to the fact that the same strategy was implemented in the intervention and control groups (individual skills). Consequently, it was not possible to infer which intervention was more effective for the outcome evaluated.
A systematic review without meta-analysis carried out with 15 studies revealed that most of them exerted a positive effect on preparing the team to deal with violent situations or on reducing the number of violent incidents, although the evidence is still scarce (59) .
In this same aspect, a systematic review with metaanalysis carried out with nine studies (clinical trials and quasi-randomized studies) found that the evidence from the studies is still extremely uncertain about the effects of education and training against aggression when compared to no intervention (13) .
Similarly, certainty of the evidence of the outcome

Conclusion
This review did not reveal high scientific evidence for the outcomes of prevention and reduction of workplace violence in relation to the interventions (individual skills, multiple approach and governmental actions) implemented, mainly due to the high and uncertain risk of bias in the studies, in addition to the high statistical heterogeneity.
Due to the impossibility of a precise scientific judgment in this meta-analysis, it is recommended to conduct more randomized clinical trials with standardization of the interventions, low risk of bias and low consistency, so that the most effective interventions can be replicated in the practice and provide a safe and decent work environment for health and support professional.